Shivering amid snow flurries and temperatures of -11C, Cheltenham Festival officials have moved to reassure punters that Tuesday's eagerly awaited opening day is not at risk from frost despite recording the coldest March since records began at the Gloucestershire course.

The Festival is normally filed alongside crocuses and snowdrops as one of the first harbingers of spring but both the Old Course and New Course were swathed in covers for the first time ever to protect the ground from temperatures that dropped to unprecedented levels on Monday afternoon once the wind chill was factored in.

With £3.8m in prize money at stake for 27 races over four days at the highlight of the National Hunt racing calendar, organisers have mobilised an army of workers and 45 acres of plastic sheeting to ensure it does not fall prey to unseasonal weather conditions that led to a low of -6C overnight on Sunday.

The clerk of the course, Simon Claisse, said that no inspection was planned despite the freezing temperatures because the 630 covers laid by 60 staff using 10,000 pegs had protected the ground, which on Monday remained soft underneath the sheets. An extra mile of rail has also been installed to prevent loose horses from damaging the plastic coverings. Claisse will walk the course on Tuesday morning after the covers come off at 10am before confirming the going.

"I think the Festival should start with soft going but I am guessing because I won't know until the frost covers are lifted and that process will start as late as possible tomorrow at 10am," he said. "The lifting of the covers on the Old Course has to be complete by 1.15pm but should be finished before then. I will then walk the course to assess the going. The lowest temperature we are forecast is -6C."

In addition to the usual rolling hills, the backdrop to Tuesday's racing will be the miles of black sheeting that is also covering the parade ring and the winner's enclosure. Caterers are expecting a run on hot food and drinks in the face of temperatures that never reached above -1.5C on Monday.

Organisers have reported strong ticket sales despite the freezing weather, with 230,000 spectators due to converge on Cheltenham over the four-day Festival. Tickets for Gold Cup day on Friday have already sold out.

At least 55,000 spectators are expected the opening day, when the card features three former winners going head-to-head in the Champion Hurdle and the keenly anticipated showdown between Simonsig and Overturn in the Racing Post Arkle Challenge Trophy Chase.

However, while the Old Course, which hosts racing on the opening two days of the Festival, and the New Course, utilised on the final two days, are protected from the frost, the cross-country course remained uncovered.

Claisse said that, while it had some frozen ground on Monday morning, it was "fine by the afternoon and has remained raceable". He added: "We've had only two races on it so far this year and we've covered up the vulnerable bits. The rest of it has got a lot of grass on it."

Immediately after racing finishes on Tuesday staff will begin re-covering the course in an operation that takes around two and a half hours.

With punters, who are expected to wager a collective £600m on the Festival over the course of the week, adjusting their picks based on the heavier ground Claisse said that it had been decided well in advance to activate the cold weather plan for the first time in light of the long-term forecast.

"We put a plan in place six or seven years ago to cover them because a fortnight out it looked as though we'd have some very cold weather," he explained.

"What is unusual about these very cold wind chill temperatures is that they are combined with very low afternoon temperatures. We have had a maximum today of one and a half degrees. For mid-March that is very unusual. It's a plan that has been in place and was mobilised at the right time."

Sprinter Sacre, the star performer who the Cheltenham managing director, Ian Renton, this week said could become jump racing's equivalent of Frankel, heads a field of seven horses declared for Wednesday's feature race, the Queen Mother Champion Chase.